漫谈矿山法隧道技术第二讲——喷混凝土

阐述了各国对喷混凝土初期强度的要求和日本的相关研究,强调在今后的隧道施工中,必须强化对喷混凝土初期强度的测试,积累有关初期强度的数据,摸清楚初期强度与变形控制的规律。喷混凝土最佳配比是确保喷混凝土质量的关键,介绍日本建议的确定喷混凝土最佳配比的试验施工流程,提出应建立喷混凝土生产线。比较详细地介绍了国外,尤其是日本对喷混凝土机械的研制及应用情况(包括:分离式喷射系统,一体式喷射系统,长臂喷射机,双喷嘴喷射机等),认为提高喷混凝土施工机械化水平,实现快速及时喷混凝土,对保证施工安全有重要作用,是保证喷混凝土质量的关键之一。列举了各国应用纤维喷混凝土的现状,认为合适的纤维补强材料可以取代金属网,应当尝试,以简化作业程序、提高喷混凝土速度和质量。介绍了日本青函隧道对喷混凝土的耐久性进行的长达40年的调查情况,认为青函隧道的喷混凝土保持了长期的耐久性。最后强调,强化对喷混凝土技术的研究和机械的开发,是目前急需解决的重要任务之一;如何确保喷混凝土的初期强度,如何建立喷混凝土生产线,是今后在施工中应予以关注的问题,这2个问题不解决,就不能确保喷混凝土在初期支护中发挥其应有的功能。

Tunneling by Mining Method: Lecture II: Shotcreting

The requirements on the initial strength of shotcrete in different countries, as well as related studies made in Japan, are presented. It is emphasized that the measurement of the initial strength of shotcrete must be strengthened in tunnel construction so as to accumulate data on the initial strength of shotcrete and acquire the correlation between the initial strength of shotcrete and the control of the deformation. It is stated that the optimum mixing ratio of shotcrete is the key to ensuring the quality of shotcreting. The flowchart of the trial to determine the optimum mixing ratio of shotcrete proposed in Japan is presented, and it is proposed that shotcreting production line should be established. The development and application of shotcreting machines (including separated shotcreting system, integrated shotcreting system, long boom shotcreting machine, and shotcreting machine with double nozzles) in foreign countries, especially in Japan, are presented in detail. It is believed that improving the mechanization level of shotcreting operation and performing rapid and timely shotcreting are very important for the tunneling safety and the shotcreting quality. The state of art of fiber reinforced shotcreting in different countries is presented. It is believed that proper reinforcing materials can replace the wiremesh and that fiber reinforced shotcreting should be tried so as to simplify the shotcreting procedure and improve the speed and quality of shotcreting. The results of the 40 year investigations made on the durability of the shotcrete of Seikan tunnel in Japan are presented and conclusion is drawn that the shotcrete of Seikan tunnel has good long term durability. Finally, it is emphasized that study on the shotcreting technology and development of shotcreting equipment are the main present tasks and how to ensure the initial strength of the shotcrete and how to establish the shotcreting production line are the main topics in the future.